Various diseases of the eye are commonly treated by frequent daily application of ophthalmic drugs for example in the form of eye drops or ointment. While this is suitable and convenient in some cases, it can be a serious disadvantage that the drug is not present in the eye in a continuous manner. With a view to overcoming this disadvantage it has been previously proposed, for example, in U.S. Pat. No. 3,416,530 of R. A. Ness assigned to Alza Corporation and subsequent patents of Alza Corporation to provide a flexible ocular insert device adapted for the controlled sustained release of the drug.
In for example U.S. Pat. No. 3,828,777 of R. A. Ness assigned to Alza Corporation it is stated that the ocular insert can be fabricated in any convenient shape for comfortable retention in the conjunctival sac of the eye and that the marginal outline can be ellipsoid, doughnut-shape, bean-shape, banana-shape, circular or rectangular; and in cross section it can be doubly convex, concavoconvex, or rectangular. It is suggested however that the original cross-sectional shape of the device is not of controlling importance. However, these previously proposed devices have in practice met with no more than limited success because most of the proposed shapes and sizes were not suitable for placement in the narrow upper and lower fornices. Also, previous devices have tended not to remain in place in the eye and have at times caused irritation to the patient during use.
U.S. Pat. No. 4,186,184 to A. Zaffaroni discloses that the length of an insert device should be from 2 to 20 mm, its width 1 to 15 mm and its thickness 0.1 to 4 mm. A wide variety of shapes are disclosed including ellipsoid, doughnut, bean, banana and square shapes.
U.S. Pat. No. 3,828,777 to Ness discloses an ocular device which is inserted in that portion of the eye bounded by the surfaces of the bulbar conjunctiva of the sclera of the eyeball and the palpebral conjunctiva of the lid. Such placement of the device would, however, be subject to eye movement and would not provide an anchored position such as is obtained in the present invention. Movement of the device causes pain, irritation, foreign body sensation and watering.
U.S. Pat. No. 4,343,787 to Katz discloses water soluble inserts for the eye in which broad dimensional ranges of sizes and shapes are employed. There is no description of an insert of a specific size and shape to allow it to be retained in the fornix portion of the eye.
U.S. Pat. No. 4,135,514 to Zaffaroni et al. relates to osmotic drug delivery devices which can be used for the administration of ocular drugs. A wide variety of shapes and sizes is disclosed.
EP-A-0 033 042 to Merck and Co., Inc. discloses ocular inserts which can take any of a variety of shapes, one of which may be an extruded rod. There is no description, however, of a device having dimensions which make it suitable for insertion into the fornix so as to be retained therein for 7 days or longer.
U.S. Pat. No. 4,730,013 to Bondi et al. discloses ocular inserts intended to overcome the problem of blurred vision arising from the use of particular insert materials. The maximum length of 5 mm employed by Bondi et al. is considerably smaller than the range of dimensions employed in the present invention. It is disclosed in this patent that a device with a length of 5 mm falls well below the minimum length required for retention in the eye of humans for 7 days or more.
EPO 0 251 680 to IOLAB, Inc. discloses a device for controlled drug release to the eye, in which an external matrix rapidly soluble in body fluids and having bioerodible microparticles containing the drug are positioned in the upper or lower conjunctival cul-de-sac of the eye. There is no description of a device which is retained in the eye for seven days or longer, or of the specific shape and dimension of the device of the invention for placement in the upper or lower fornix.
U.S. Pat. No. 3,845,201 to Haddad et al. discloses an ocular device for insertion in the cul-de-sac of the conjunctiva. The device may be any of various shapes, preferably disc shaped.
U.S. Pat. No. 4,164,559 to Miyata et al. discloses soluble device for drug delivery to the eye including collagen insert having an ovoid shape. The device is described as insertable into the inferior fornix. There is no description of a device having the dimensions employed in the present invention for retention of seven days or longer.
U.S. Pat. No. 4,179,497 to Cohen et al. discloses water soluble inserts of various shapes for applying drugs to the cul-de-sac of the conjunctiva. Again there is no description of an insert having the specific dimensions of the invention.
In the use of a prior art device known as Ocusert, the subject of U.S. Pat. No. 3,828,777 to Ness, the device is inserted into the conjunctival cul-de-sac. Either of two systems may be employed, with the Pilo-20 system measuring 5.7.times.13.4 mm on its axes and 0.3 mm in thickness and the Pilo-40 system measuring 5.5.times.13 mm on its axes and 0.5 mm in thickness. Various problems in retention and irritation which occurred in the use of this device are documented, for example, in the following publications: P. Sihvola et al., Practical problems in the use of Ocusert-pilocarpine delivery system, Acta Ohthalmol. (Covenh.), December 1980, 58 (6), pp 933-937; S. E. Smith et al., Comparison of the pupillary, retractive and hypotensive effects of Ocusert-40 and pilocarpine eyedrops in the treatment of chronic simple glaucoma, Br. J. Oohthalmol., April 1979, 63(4) pp 228-232; and I. P. Pollack et al., The Ocusert pilocarpine system: advantages and disadvantages, South Med. J., October 1976, 69 (10), pp 1296-1298.
Other ocular inserts are described in the following literature reports: Urtti et al. (1990) Controlled drug delivery devices for experimental ocular studies with timolol.1.In vitro release studies. Int. J. Pharm., 61, 235-240; and Urtti et al (1990) Controlled drug delivery devices for experimental ocular studies with timolol.2.Ocular and systemic absorption in rabbits. Int. J. Pharm., 61, 241-249. These reports describe the use of a permeable hollow tube (silicone) for ocular delivery. The tube has a diameter of 1.94 mm which is outside the dimensions employed in the present invention. Also, the device was only observed in the eye for an 8 hour period.
EP-A-0,262,893 discloses a flexible ocular insert device adapted for the controlled sustained release of an ophthalmic drug into the eye, which comprises a body having a thin elongated circular cylindrical configuration, the device having for example a length of at least 8 mm and a diameter not exceeding 1 mm. The circular cylindrical body terminates at transverse end surfaces which may for example be planar or domed.
Previously published U.S. Pat. No. 5,395,618 discloses a flexible ocular insert device adapted for the controlled sustained release of an ophthalmic drug upon insertion into the upper or lower fornix of the eye, said device comprising an elongated body of a polymeric material in the form of a rod or tube containing a pharmaceutically active ingredient and with at least two anchoring protrusions extending radially outwardly from said body, said device having a length of at least 8 mm and a diameter including protrusions not exceeding 1.9 mm, wherein said device is sufficiently flexible to allow it to bend along the curvature of the eye within the upper or lower fornix upon being positioned so that the longitudinal axis of said device is generally parallel to the transverse diameter of the eyeball, said device being of a size and configuration such that, upon insertion into the upper or lower fornix, the device does not extend onto any visible portion of the eyeball, said device being independent of movement of the eye and remaining out of the field of vision so as to be well retained in place and imperceptible by the patient over a prolonged period of use, said protrusions acting to minimise lateral movement of the device within the fornix, whereby the device when inserted into the upper or lower fornix can be retained therein for more than seven days.
However, their retention is sub-optimal as far as comfort, adverse effects, movement within the fornix felt by the patient, foreign body sensation and irritation in general.